The lens system of this invention comprises a pair of lenses, the first a negative meniscus lens and the second a positive meniscus lens, adapted to be placed on either side of a commercial projection head for an overhead projector to change the focal length of the objective lens and the magnification to increase the projection distance from 8 feet (244 cm) to 15 feet (457.2 cm).
Projection systems are known which utilize four elements in an objective lens but no prior art is known wherein a pair of lenses are provided which can be mounted in spaced relationship to the existing projection lenses in an overhead projector to produce a new lens system which can be utilized with the existing standard projection equipment without changing the standard position of the rear lens to the copy plane or make other equipment modifications.